What are the diagnostic criteria and methods for pelvic inflammatory disease (PID)?

Diagnostic Criteria and Methods for Pelvic Inflammatory Disease (PID)

PID should be diagnosed using a low threshold approach, with treatment initiated based on minimum clinical criteria of lower abdominal tenderness, bilateral adnexal tenderness, and cervical motion tenderness in sexually active women at risk for STDs. 1, 2

Minimum Diagnostic Criteria

• Lower abdominal tenderness 3
• Bilateral adnexal tenderness 3
• Cervical motion tenderness 3

The CDC's 2002 guidelines updated these criteria to indicate that empiric treatment should be initiated in sexually active young women and other women at risk for STDs if they present with either:

• Uterine/adnexal tenderness or
• Cervical motion tenderness 3, 2

Additional Criteria to Increase Diagnostic Specificity

Routine Criteria (Simple to Assess)

• Oral temperature >38.3°C (>101°F) 3, 2
• Abnormal cervical or vaginal mucopurulent discharge 3, 2
• Presence of white blood cells (WBCs) on saline microscopy of vaginal secretions 2
• Elevated erythrocyte sedimentation rate (ESR) and/or C-reactive protein (CRP) 3, 2
• Laboratory documentation of cervical infection with N. gonorrhoeae or C. trachomatis 3, 2

Elaborate Criteria (More Definitive but Expensive/Invasive)

• Histopathologic evidence on endometrial biopsy 3
• Tubo-ovarian abscess on sonography 3
• Laparoscopic abnormalities consistent with PID 3

Diagnostic Algorithm

1. Initial Assessment: Evaluate for minimum criteria in sexually active women with pelvic or abdominal pain 1, 2

2. Laboratory Testing:

   • Cervical cultures or non-culture tests for N. gonorrhoeae and C. trachomatis 3
   • Complete blood count 4
   • C-reactive protein 4

3. Imaging:

   • Pelvic ultrasound is not sensitive or specific for uncomplicated PID but should be performed to look for complications (e.g., tubo-ovarian abscess) or alternative diagnoses 4
   • Abdominal-pelvic CT with contrast may be useful for differential diagnosis when diagnostic uncertainty exists 4

4. Advanced Diagnostics (for severe cases or diagnostic uncertainty):

   • Endometrial biopsy 3
   • Transvaginal sonography 3
   • Laparoscopy (not recommended solely for diagnosis) 4

Important Clinical Considerations

• No single historical, physical, or laboratory finding is both sensitive and specific for the diagnosis of PID 3
• Many episodes of PID go unrecognized due to mild or nonspecific symptoms 3, 1
• The clinical diagnosis of PID is imprecise, with a positive predictive value of approximately two-thirds when compared with laparoscopy 3, 5
• Absence of hyperleukocytosis or normal CRP does not rule out the diagnosis of PID 4
• Most women with PID have either mucopurulent cervical discharge or evidence of WBCs on microscopic evaluation of vaginal fluid 3
• If cervical discharge appears normal and no white blood cells are found on wet prep, the diagnosis of PID is unlikely 3

Common Pitfalls and Caveats

• Using highly sensitive PID diagnostic criteria means many women without PID may be misdiagnosed and treated unnecessarily (low specificity) 3
• Careful follow-up is necessary; if no clinical improvement occurs within 48-72 hours, alternative diagnoses should be considered 3, 1
• Even minimum clinical criteria may exclude some women with PID; clinicians should not withhold therapy if PID is suspected despite failure to meet all criteria 3
• Waiting for imaging should not delay the initiation of antibiotic therapy 4
• Laparoscopy is not recommended for the sole purpose of diagnosing PID 4
• When cephalosporins are used in treatment, appropriate coverage for Chlamydia trachomatis should be added since cephalosporins have no activity against this organism 6, 7